Earlier this year, Swedish startup Wavebreaker started operations with the launch of its traffic noise sound damper of the same name. Founder and developer of Wavebreaker Tony Johansson spoke with RailTech.com about the system and the benefits thereof.
For Johansson, Wavebreaker is the culmination of more than 32 years of experience in the field of acoustics. Back in 2017, he took the plunge by starting his own business. With support of Swedish business incubators such as Almi, Vinnova and InfraSweden2030, Johansson was able to perfect his Wavebreaker prototype ahead of installation as part of a pilot project in Stockholm.
Wavebreaker utilises the principle of acoustic interference, where noise enters a series of channels of varying length before coming out at the other end. With Wavebreaker, this means noise from a passing tram or tram enters at the front and exits at the top. There it ‘interferes’ with the noise travelling over the Wavebreaker. In doing so, the so-called noise paths cancel each other out.
“It’s bit like what you get with noise cancelling headphones, but then without the need of a power source. It is a passive system and as such only needs the input of traffic noise to function”, Johansson explains. Wavebreaker is optimised for reducing train noise by focusing on the spectrum between 400 to 4000 Hz.
During trials in Stockholm in August 2021, Wavebreaker resulted in a noise reduction of 5 dBA. Also in terms of psychoacoustics, or the way humans perceive sounds, there was a marked improvement. “The familiar high-pitched rattling sound that you associate with trams of trains was softened with Wavebreaker”, Johansson says.